bed rail height

57" is on the low side. IIRC the new Rams are around 60-61". Should be fine.

Heck that is the height of my 2001 Ram 4X4 I am going to install a correct track kit to get 2' lift on my 05 Copper Canyon so i am right at level.

No worries. I pull a Grand Design Reflection 337RLS with my '13 F350. My bed rails are at 56.5" and my FW is towing level. I have approximately 7 inches of clearance at the bed rails. I've put on 11K miles so far and I've never had a clearance issue. Please note that my 337 has 16" rims. Some of the smaller Grand Design Reflections have 15" rims and smaller tires which could result in a little less clearance.

I sweated my Bed Rail height. I also ended up with 57". I have 8.5" clearance between the bed rail and 5ver overhang. A lot will probably depend upon the 5ver design. Spend time with a tape measure. Measure from the King Pin to the 5ver overhang. Then determine how high the King Pin will be in the truck bed. This will give you an idea if you will be OK.

You will be fine. I have 6 to 8 in bed rail clearance and my trailer rides level.